This invention relates to a trimming device for a marine propulsion unit and more particularly to an improved connection between the trim unit and the outboard drive.
In a wide variety of outboard drives, both outboard motors and the outboard drive section of an inboard/outboard drive, there is an arrangement incorporated for adjusting the trim position of the pivotally supported outboard drive. In one form of powered trim adjustment, a trim cylinder is carried by the transom of the watercraft and has an actuating rod or thrust member that engages the outboard drive and which urges it about its pivotal axis to change the trim position. In addition, the thrust member of the trim unit takes the driving thrust from the outboard drive during forward propulsion. Normally, the thrust member reciprocates along a fixed axis whereas the outboard drive pivots about a fixed axis. As a result of this, there will be relative movement between the thrust member and the outboard drive that can result in wear, galling and other unsatisfactory conditions. In addition, such relative movement causes noise during operation.
It has been proposed to relieve the aforenoted condition through the use of a ball or roller member that is carried by the trim thrust member and which engages the outboard drive for effecting its pivotal movement. Although such roller members have some advantages, they have the disadvantage of providing a very small contact area and, therefore, a very high unit stress at the point of force transmission. Therefore, this solution can, at times, aggravate the galling and wear situation rather than reducing it.
It is, therefore, a principal object of this invention to provide an improved thrust and trimming device for a marine propulsion unit wherein wear is reduced.
It is a further object of this invention to provide a thrust taking arrangement for a trimming unit of a marine propulsion device wherein the contact area for force transmission is substantially increased thus reducing unit loading.
It is a further object of this invention to provide a simple and yet effective arrangement for transmission thrust between a thrust member and the outboard drive of a marine propulsion unit.
In connection with trimming devices of the type described, it is obvious that wear will be an eventual outcome regardless of the design of the system. Of course, it is desirable to construct the arrangement so that wear will be minimized but also it should be insured that replacement of worn components can be easily effected.
It is, therefore, yet another object of this invention to provide an improved arrangement for a trimming device for a marine propulsion unit wherein worn components can be easily serviced.